DALLAS - Details of disturbing letters targeting teachers and a student have emerged at a Dallas elementary school.

The sexually-charged notes have been mysteriously showing up at the school over the past few months.

Now teachers are demanding extra security.

The school district is investigating how these crude and very graphic letters started appearing up at George Truitt Elementary School.

While they've been popping up for months, DISD has just started looking into the situation this week.

More than a dozen handwritten letters, that appear to be scripted by a child, have been showing up on doorways and desks, detailing sex acts the person wants to perform on certain teachers.

Some even have crude drawings of body parts.

"There's a possibility that whoever is doing this could be in the building and could take it at a different level at some point in time," a union representative said.

Teachers at the school were warned by administrators not to talk to us but their union has heard an earful.

A number of female educators are frightened to be alone on the school's campus.

We saw them Friday walking in groups and asking male employees to escort them to their cars.

"They are really afraid being in the building, we hope that the district will beef up the security and have more security around the portables where most of the activity is taking place," the union representative said.

One of them targets a student at the school.

It even states the person knew where she lives.

Despite the concerns, parents were unaware of the problem.

"It's real scary, especially having my kids going up here. It's scary as a parent," said one.

This week, the district launched an investigation into the concerns.

Officials say it's not clear whether an actual crime was committed but it is clear the letters have no place in the building.

"Whether this is an adult using a child's handwriting, whether this is a child thinking this is appropriate, it's disturbing that this is taking place at an elementary school with very young children," the union representative said.

E-mail ccivale@wfaa.com.